The Scofield Report. How concrete contributes to today s Green designs

Transcription

1 Concrete The Scofield Report Sustainable Construction Sustainability Decorative Concrete: How concrete contributes to today s Green designs

2

3 Sustainability embodies many different aspects of environmentally friendly methods in supplying goods and services in nearly every aspect of our lives, from agriculture to energy production and use to manufacturing of building products and design of the built environment. Light colored exterior surfaces reflect sunlight, leading to cooler pavements and reducing air conditioning costs as much as 18%. With the ever-present issues of climate change and environmental protection, the public has started to embrace sustainable development. Developers who have never considered sustainability are finding that green buildings are easier to lease, command higher prices, and generate good public relations. They are also realizing that sustainable design and construction doesn't have to come at a premium. A 2007 study by architectural firm Davis Langdon, The Cost of Green Revisited ( found no significant difference in cost between green buildings and those designed and built without considering sustainability. Many project teams are building green buildings with little or no added cost, reported Davis Langdon, and with budgets well within the cost range of non-green buildings with similar programs. According to Michael Deane with global construction giant Turner Construction, a LEED silver rating adds only 2% to the initial cost of a building and a LEED platinum rating adds only about 6%. The U.S. federal government has defined sustainability through its Whole Building Design Guide, which establishes a set of "Guiding Principles for Federal Leadership in High Performance and Sustainable Structures." Those are: Employ integrated design to establish environmental performance goals and consider all stages of the building's lifecycle. Optimize energy performance using a whole building approach. Protect and conserve both indoor and outdoor water. Enhance indoor environmental quality through better ventilation, thermal control, and moisture control; better use of daylighting; and use of low-emitting materials. Concrete, and in particular decorative concrete, is an important part of achieving these goals. In this paper, and throughout the series of Scofield Reports to follow, we will examine how knowledgeable design and construction can lead to high-performing, environmentally sound buildings. We will provide designers with ideas and tips on design features that can increase a building's sustainability and show how concrete contributes. We will look at how concrete can: Colored ground & polished concrete floors are nontoxic and low maintenance. Photo: T.B. Penick & Sons reduce life cycle costs optimize energy use reduce construction waste utilize recycled content use locally produced materials reduce the quantity and increase the quality of stormwater runoff lower heat island effects improve indoor air quality In this report, we will also describe how sustainability is documented, through the use of LEED credits or through Green Globes, an alternative rating system. These rating systems provide a means for quantifying sustainability that focuses the designer's attention on most of the important aspects of building green. SCOREP or L. M. Scofield Company 2008 All rights reserved. 1

4 The world's built environment is the basis for human civilization. Building and construction provides 5 to 10% of world employment and contributes 5 to 15% of GDP, according to the United Nations' Environment Programme. In a recent report, Building and Climate Change, the UNEP also notes, however, that buildings consume 30 to 40 % of the world's energy and that more than 80% of that is consumed during operation rather than construction, meaning that energy efficiency is critical to reducing our buildings carbon footprint. At the end of its service life, concrete can be recycled for fill or as aggregate for new concrete. Photo: The Concrete Producer The built environment also is a significant consumer of water--20% of the world's water, according to UNEP, goes to buildings and construction. This sector also accounts for 30-40% of the world's solid waste generation and stormwater runoff from urban areas is a major source of water pollution. Green design and construction makes sense both for our stewardship of the earth and at the bottom line as energy prices continue to rise. Concrete is an extremely versatile and sustainable building product, with the following qualities: The raw materials used in concrete are abundant and usually locally available. Extraction of this material can be managed to have minimal impact or be mitigated by reclamation. Cement production has become much more energy efficient to where today it accounts for only 0.33 percent of U.S. energy consumption and results in only about 1.5% of U.S. CO2 emissions. Concrete is produced locally and you can get the exact amount needed with little waste. Concrete is durable and is resistant to rot, corrosion, moisture, fire, and the elements in general, making for very low life-cycle costs. Concrete provides buildings with thermal mass that contributes to energy efficiency. As interior walls and floors, concrete has no detrimental effect on indoor air quality. Concrete can be colored, stained, stamped, or ground & polished, reducing the need for other materials such as siding, tile, and carpeting. Exterior concrete hardscapes, available in nearly any color or texture, are extremely durable and nearly maintenance free. Decorative concrete hardscapes serve as appealing gathering areas. Pervious concrete pavement can help manage storm water and reflects heat to reduce heat-island effects. Light-colored concrete, with its high albedo (light reflectance) is much better than black asphalt or roofing at reflecting sunlight and reducing surface temperatures. This results in cooler pavements and roofs (overcoming heat-island effects). Waste materials (such as fly ash or slag) can be incorporated into concrete. SCOREP or L. M. Scofield Company 2008 All rights reserved. 2

5 Today, sustainable design and construction is generally a volunteer effort, although cities including Chicago, Austin, Seattle, and Portland and states are beginning to adopt green construction requirements. As owners, and the public at large, demand sustainable buildings and features, there will be increasing reliance on systems that quantify the greenness of a project. There are currently four organizations that have rating systems for documenting sustainability of new buildings. The four national rating systems are: administered by the U.S. Green Building Council, administered by the Green Building Initiative National Association of Homebuilders Building Guidelines administered by the Environmental Protection Agency Interior concrete floors and walls retain heat to reduce the required size of heating and cooling systems. Photo: National Building Museum Liquid Stone Exhibit Of these four rating systems, the two most commonly used for commercial construction are LEED and Green Globes, with LEED gaining most of the attention. Although similar in many ways, and allocating points mostly for the same green attributes, these programs have some distinct differences: For residential buildings, either LEED for Homes or the NAHB Guidelines can be used, and there are also local programs developed by local home-builder groups or individual cities. The NAHB Guidelines were developed with heavy involvement by the building industry. The NAHB is currently working with the International Code Council to get these guidelines adopted under the American National Standards Institute as a national green building standard. Registering a building for potential LEED certification costs $450 (for USGBC members). The fees for certification are based on building size and range from $1750 for buildings less than 50,000 square feet to $17,500 for buildings over 500,000 square feet (member price). The GBI says that Green Globes certification costs $4500 to $6000 for full verification. There are multiple LEED rating system platforms (including new construction, existing buildings, interiors, schools, retail buildings, healthcare, and homes). Currently in the pilot stage is a new program, LEED for Neighborhood Design, focusing on site selection and land planning. Each of these platforms awards sustainability points for different characteristics of a project. To get a project certified under LEED for new construction (LEED-NC), there are several prerequisites (such as mandatory recycling and minimum energy performance), then additional points are earned for various building features. Points are gained in five categories: sustainable sites (14 points), water efficiency (5 points), energy & atmosphere (17 points), materials & resources (13 points), and indoor environmental quality (15 points). There is a sixth category for innovative design features that can earn up to another 5 points. Earning points allows a building to move up from simply certified (which requires 26 points) to silver (33 points), gold (39 points), or platinum (52 points). The GBI administers the Green Globes system for commercial buildings. Green Globes is a web-based online sustainable-building assessment tool that is set up in a very user-friendly questionnaire style. A building designer enters information into the Green Globes assessment tool in seven categories, including project management, site, energy, water, and indoor environment. The online tool provides feedback and tips on increasing sustainability points. A building is rated from 0 to 4 Globes depending on what percentage of the possible points are attained (1 Globe is 35% up to 4 Globes which is 85% of possible points.). With all of these rating systems, buildings are self-assessed, then the assessment is verified by the rating organization (USGBC or GBI) or by someone who has been accredited by one of those organization. With LEED, most designers enlist the assistance of someone who has the LEED Professional Accreditation (LEED PA), meaning they have been tested and proven to understand the basis of sustainable design and the intricacies of the LEED system. There are currently about 45,000 LEED APs and 10,000 projects currently in the LEED system, with more than 5000 project registered in 2007 alone. SCOREP or L. M. Scofield Company 2008 All rights reserved. 3

6 As noted previously, green building design and construction today is mostly a volunteer effort. But that is beginning to change. Washington D.C. recently passed the Green Building Act of 2006, requiring commercial developers in the nation's capital by 2012 to meet LEED certification criteria for any building greater than 50,000 square feet. Chamblee, Ga., a suburb of Atlanta, now requires all private development 20,000 square feet or greater to become LEED certified in addition to all future municipal buildings, regardless of size. Green schools increase student attendance and the higher indoor air quality reduces asthma. Schools have become a major focus for green construction. In July 2007, the U.S. Conference of Mayors unanimously passed a resolution calling on all schools in the United States to be green within a generation and at least 6 states and the District of Columbia require green school construction. In Ohio, the LEED for Schools rating system is now part of the school design standards and the Ohio School Facilities Commission estimates the state will save over $1.4 billion in operating costs over the next 40 years through reduced energy consumption. A recent national study (Greening America s Schools: Cost and Benefits) found that green schools increase student attendance by 5 to 15% and the higher indoor air quality reduces asthma by 38%. A Capistrano, Calif., study found that increased daylighting alone resulted in faster learning: 20% for math and 26% for reading. In many states, tax credits are available for green construction and even bankers are getting into the act. USBanker magazine reported that "Banks like PNC Financial Services and Bank of America are at the forefront of the green-building craze." All this adds up to the fact that sustainable construction is not a fad but is here to stay. Everyone in the construction industry will either have to go green voluntarily or have it forced on them being ahead on this issue has become a distinguishing characteristic of a progressive company. Passive solar elements, such as this Trombe wall, can retain solar energy and reduce heating loads. Precast concrete panels with integral color were used to construct office buildings for engineering company CH2M Hill that were recognized for construction efficiency and optimal energy performance. Photo: CH2M Hill SCOREP or L. M. Scofield Company 2008 All rights reserved. 4

7 Life cycle analysis (LCA) tends to favor concrete as a construction material, since concrete is so durable and recyclable. LCA, however, is not currently a part of any of the rating systems, although both USGBC and GBI are currently considering how to change that. In January 2009, the USGBC will debut LEED 2009, a reorganization of the commercial guidelines that s simpler and elegant and committed to continuous improvement, according to the USGBC s Ashley Katz. Still under consideration for inclusion is how to incorporate life cycle analysis. In both LEED and Green Globes, the use of concrete can result in considerable points towards increasing the rating of a building or development. Here's how: Polished and stained interior floors emit no toxic gases and can t harbor mold or dust mites. Photo: Colorado Hardscapes : A high-point attribute of buildings in either LEED or Green Globes is energy efficiency. To evaluate this, a complete energy analysis of the building is needed. Concrete walls and floors contribute considerable thermal mass to buildings, which reduces the overall energy load and the required size of heating and cooling systems. Exposed concrete, such as decorative concrete floors or architectural concrete walls, is the best heat-retaining material available. Also, buildings with concrete walls are very airtight, which makes them considerably more efficient in an overall building analysis. One very efficient heating system is radiant heating--decorative concrete floors are ideal for this application. : Today's efficient concrete construction techniques generate very little waste. Formwork is reusable and concrete can be ordered in precise quantities. Excess concrete can easily be crushed and used as fill on site. : Incorporating post-industrial waste into building materials earns points under LEED credit MR-C4 and Green Globes credit E.2.2. Fly ash and slag, waste materials from power generation and steel making, respectively, are important constituents of most modern concrete mixtures and LEED provides extra points for using these materials. Post-industrial wastes are also used in the manufacture of color pigments for use in concrete. Pervious concrete captures and treats surface waters, reducing the pollution load on nearby waterways. Photo: Cemstone This concludes the Scofield Report on How Concrete Contributes to Today's Green Designs. For more information, or to contact a Scofield Representative, call This paper was researched and written by William D. Palmer Jr. and Paul M Newman from Complete Construction Consultants ( : LEED awards up to 2 points for use of regionally produced materials. Nearly all ready-mixed concrete, and most of the aggregate and cement, is produced regionally (within 500 miles). : Pervious concrete surfaces are one of the best alternatives for managing stormwater, since all runoff from a site can easily be eliminated--that's worth 1 LEED point. Another point is available for treating the runoff. That is also possible to do with pervious concrete, where bacterial communities develop within the pervious matrix that can degrade wastes of all kinds, including petroleum products. (See the Scofield Reports on colored pervious concrete for more details.) : Points are available in LEED and Green Globes for the use of low-emitting materials--that is, materials that do not off-gas toxic substances during the life of the building. Carpet, adhesives, and paints are all on LEED's list of potentially harmful materials--none of these are necessary with concrete interiors. Colored, decorative concrete floors emit no toxic materials, are perfect for radiant heating systems, and never need to be replaced. And modern materials used to produce decorative concrete floors have very few toxics: water-based stains and sealers and ground & polished floors are LEED-friendly. SCOREP or L. M. Scofield Company 2008 All rights reserved. 5